ASTR 310: Lecture 2 Logistics

ASTR 310: Lecture 2 Logistics ● Course web page (see blue handout) ● www.astro.ubc.ca/people/gladman/a310 ● Lectures are username/password : a310/selene ● Textbook review (see web and handout) ● Did you get an email yesterday from me? IF NOT ● you just signed up for the course, or ● you didn't look at your email, or ● your email address in the SSC is wrong! ● Math review (on web site). Help today 2:00-4:00. ● You should sign up for Mastering Astronomy, and enroll in the course MasteringMastering AstronomyAstronomy introintro www.masteringastronomy.com New Student Access code in book or from bookstore or online (see course web page) MAKE SURE your UBC ID goes in Join course : a310ubc2011sep Assignments 2 and 3, due 6 AM Monday Assign. 1 not for credit, do this weekend. ASTR 310 The routine 1) Make note of readings for next class See course web page for the page number DO the readings, then look for the quiz 2) The Mastering Astronomy quiz goes live 2 PM (on each day there is a lecture) 1)Reading quiz appear at end of each class This is the material to be done NEXT lecture 2)Due at *6 AM* due date will the norm... 3) I adapt lectures to places you have troubles (this is called “Just in Time Teaching”) WhyWhy dodo wewe dodo this?this? On the questionnaire, many students said something like: “ I've heard that if you do the readings and keep up this is a course that is not too hard to get a good grade in.” This is CORRECT! We've actually SHOWN this makes a big difference! Comparison using two methods for this course. MAMA gradinggrading policypolicy (You can read this at the top of every assignment on the Mastering web site) If you answer the Q right first try, you get full points. If not a T/F, you can try again for reduced points Max tries is : Number of responses minus 1 (if applicable) OR Three Some Q's have 'Hints'. If you answer without opening any hints: +2% If unsure, better to open hints. Once open, FINISH the hint. MAMA gradinggrading policypolicy For non multiple-choice or T/F (eg. Ranking, matching) : Each try which is wrong loses 20% of score Maximum 3 tries also LATE PENALTY -10% for every hour (or portion thereof) after 6 AM Can never get worse than -70% penalty ASTR 310: Lecture 2 Start of term Mastering So you have TWO assignments due Monday 6 AM (one is for today's lecture, so easier!) I suggest you do them one assignment at a time. Do the intro assignment too...make SURE that the 'numeric answers' question works well. YourYour locallocal sky:sky: OrientationOrientation You can use the compass directions to orient yourself. (how do you tell north?) The ZENITH is the point directly overhead. The MERIDIAN cuts the sky from north to zenith to south. ALTITUDE is the angle directly above the horizon TheThe conceptconcept ofof thethe celestialcelestial spheresphere When you look up at the sky at night, are you conscious of depth? TheThe conceptconcept ofof thethe celestialcelestial spheresphere When you look up at the sky at night, are you conscious of depth? No. The stars appear to be speckled over a globe. It is easy to imagine that this is a sphere that we live inside of, looking out. TheThe conceptconcept ofof thethe celestialcelestial spheresphere When you look up at the sky at night, are you conscious of depth? No. The stars appear to be speckled over a globe. It is easy to imagine that this is a sphere that we live inside of, looking out. Almost all ancient peoples thought this. AA modelmodel (theory)(theory) ofof realityreality Many ancient peoples thought of the dome of the sky as a physical reality A colossal `celestial sphere' that the Earth sits inside of The unchanging stars are 'fixed' on the inside of this sphere. Don't get confused...we are looking OUT from the Earth at the INSIDE of this sphere. [Not like a globe's surface, which we look 'down on'] ConstellationsConstellations areare starsstars fixedfixed onon thethe celestialcelestial spheresphere This is just making up patterns, but useful orientation Stars are at VERY different distances; in projection. ConstellationsConstellations areare starsstars fixedfixed onon thethe celestialcelestial spheresphere This is just making up patterns, but useful orientation Stars are at VERY different distances; in projection. TheThe constellationconstellation ofof OrionOrion StarsStars projectproject intointo patternspatterns onon thethe celestialcelestial spheresphere CelestialCelestial spheresphere hashas twotwo polespoles What causes the poles? Earth'sEarth's rotationrotation causescauses poles!poles! Earth turns from west to east (you are carried eastward). Earth'sEarth's rotationrotation causescauses poles!poles! Earth turns from west to east SO Sphere rotates east to west... This is called the DIURNAL CYCLE NCP,NCP, SCP,SCP, celestialcelestial equatorequator NPC, SCP are imaginary points on the sky Celestial equator halfway between (extension of Earth's out to celestial sphere). Imagine putting a grid on the sphere like latitude and longitude. LikeLike LatitudeLatitude andand LongitudeLongitude onon EarthEarth Degrees latitude and longitude So embed the Earth inside the celestial sphere • Extend the lines of lat/long out to space. Earth inside the celestial sphere • Extend the lines of lat/long out to space. • Declination =latitude • Right Ascension =longitude Coordinate systems • See Figure S1.10 (page 97) of the text to compare – Local observer coordinates (alt/az) – The terrestrial latitude and longitude – right ascension and declination The problem with altitude/azimuth • Stars move across the sky! So altitude and azimuth (angle around the horizon) change constantly. • These images (open camera shutter looking at stars) are called `star-trail' images. • We are seeing diurnal motion (caused by what?) Northern sky animation Stars rise and set as the celestial sphere spins • Or, at least, many do • It depends on where you are on Earth! Star trails, looking North Taken from the northern United States A. circumpolar stars (which never set). B. you see the NCP C. you see Polaris Right ascension and Declination • Declination is from -90° S to +90° N. Easy. • Right Ascension (RA) run around celestial equator. RA=0 at spring equinox • (we'll come back to this) RA goes from zero hours to 24h, increasing east. Each hour divided into 60 minutes (min) of time and each min into 60 seconds. Remember ; Stars have FIXED RA and DEC !!! We could thus use SIDEREAL TIME • Non-circumpolar stars always: • rise in the east • climb higher, • cross the meridian • set in the west. • The RA of stars on the meridian is called the local sidereal time. • One hour later, the RA of stars on the meridian goes up by 1 hour of RA. more on sidereal time • 24 hr of RA per day • One sidereal day later the same star will 'transit' (cross) your local merdian • Show a transit telescope • intervals are very close to solar time...more next week. Star trails to East, wide angle. Star trails to East, wide angle. Star trails to South, from Kilimanjaro • circumpolar stars near SCP also. • There is no star near the SCP. • Where can you see both celestial poles at the same time? Q: Where can you see both celestial poles at the same time? A) From the Earth's north pole B) From the Earth's south pole C) From anywhere on the equator D) From no place on Earth. From the Equator Paths of stars : View 1 Back to star paths. Think about what this looks like while standing on Earth. An easy one first: The north pole. Next, from the Equator Next, from the Equator • Are there any circumpolar stars? Now, from the northern hemisphere Now, from the northern hemisphere • In this example, latitude = 40° • Which stars are circumpolar?.

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